[AArch64][SME2] Extend SMEABIPass to handle functions with new ZT0 state (#78848)

updateNewZAFunctions is extended to generate the following on entry to a
function with either the "aarch64_pstate_za_new" or "arm_new_zt0"
attribute:
- Private-ZA interface: commit any active lazy-saves & enable PSTATE.ZA.
  - "aarch64_pstate_za_new": zero ZA.
  - "arm_new_zt0": zero ZT0.

Additionally, PSTATE.ZA should disabled before returning if the function
has a private-ZA interface.